Social network Pinterest — where users share images on virtual bulletin boards — experienced 4,000 percent growth from July to December, even though it's still invitation-only. The meteoric rise is reminiscent of Facebook. "Pinterest is part of a broader trend toward valuing content curators," said Steven L. Johnson, assistant professor of management information systems at Temple's Fox School of Business. "Back in the early days, the biggest thing was finding interesting things. Today, the problem is the opposite. We're inundated, so we're trying to find information sources we can trust."